ABSTRACT
In order to improve the noise ratio and stability of the amplified small-signal in microwave-induced thermoacoustic tomography,an amplifying circuit with wide band and high voltage gain is designed in this paper.The results show that the voltage gain is up to 80dB and the bandwidth is about 7MHz.
ABSTRACT
PURPOSE: Preamplifier and amplifier are very important parts for developing a portable counting or imaging gamma probe. They can be used for analyzing pulses containing energy and position information for the emitted radiations. The commercial Nuclear Instrument Modules (NIMs) can be used for processing these pulses. However, it may be improper to use NIMs in developing a portable gamma probe, because of its size and high price. The purpose of this study was to develop both preamplifier and amplifier and measure their performance characteristics. MATERIALS and Methodes: The preamplifier and amplifier were designed as a charge sensitive device and a capacitor resistor-rsistor capacitor (CR-RC) electronic circuit, respectively, and they were mounted on a print circuit board (PCB). We acquired and analyzed energy spectra for Tc-99m and Cs-137 using both PCB and NIMs. Multichannel analyzer (Accuspec/A, Caberra Industries Inc., Meriden Connecticut, U.S.A) and scintillation detectors (EP-047 (Bicron Saint-Gobain/Norton Industrial EP-047 (Ceramics Co., Ohio, U.S.A) with 2"x2" NaI (T1) crystal and R1535 (Hamamatsu Photonics K.K., Electron Tube Center, Shizuoka-ken, Japan) with 1"x1"NaI (T1) crystal) were used for acquiring the energy spectra. RESULTS: Using PCB, energy resolutions or EP-047 detectors for Tc-99m and Cs-137 were 12.92% and 5.01%, respectively, whereas R1535 showed 13.75% and 5.19% of energy resolution. Using the NIM devices, energy resolutions of EP-047 detector for Tc-99m and Cs-137 were measured as 14.6% and 7.58%, respectively. However, reliable energy spectrum of R1535 detector could not be acquired, since its photomultiplier tube (PMT) requires a specific type of preamplifier. CONCLUSION: We developed a special preamplifier and amplifier suitable for a small sized gamma probe that showed good energy resolutions independent of PMT types. The RESULTS indicate that the PCB can be used in developing both counting and imaging gamma probe.
Subject(s)
Connecticut , Ohio , Optics and PhotonicsABSTRACT
The therapeutic efficacy of antipsychotic drugs is generally attributed to their ability to block dopamine D2 receptors. Classical D2 antagonists are not effective to treat negative symptoms and produce extrapyramidal side effects. On the other hand, atypical antipsychotic agents ameliorate negative symptoms without producing extra-pyramidal side effects, and it is reported to be associated with blockade of serotonin 5-HT2 receptors. The purpose of this study was to evaluate the effect of risperidone on neuroreceptors in the rat brain by quantitative autoradiography method. In acute treatment group, risperidone was injected into peritoneal cavity of male Wistar rats with dose of 0, 0.1, 0.25, 0.5, 1,0 and 2.0mg/kg in each Group(5/group), and they were decapitated after 2 hours. In chronic treatment group, risperidone was injected with dose of 0, 0.1, and 1mg/kg(I.P.) for 21 days and decapitated after 24 hours following last treatment. The effect of risperodone on the binding of [3H]spiperone to 5-HT2 and D2 receptors were analysed in 4 discrete regions of the striatum, nucleus accumbens, and frontal cortex by quantitative autoradiography. Acute treatment with risperidone reduced cortical 5-HT2 specific [3H]spiperone binding to 32% of vehicle-treated control. Subcortical 5-HT2 specific [3H]spiperone binding was not affected at all dose groups whereas a significant reduction (57%) in D2 specific [3H]spiperone binding was observed in risperidone treated group at doses of l-2mg/kg. Chronic treatment with risperidone produced a decrease in the maximal number of cortical 5-HT2 receptors to 51% and 46% of control in 0.1mg/kg & 1mg/kg treated group respectively. In conclusion, risperidone is a cortical serotonin receptor antagonist with relatively weak antagonistic action on dopamine receptors. These effects on neuroreceptors may explain the therapeutic effect of risperidone as a atypical antipsychotic agents.
Subject(s)
Animals , Humans , Male , Rats , Antipsychotic Agents , Autoradiography , Brain , Dopamine , Hand , Nucleus Accumbens , Peritoneal Cavity , Rats, Wistar , Receptors, Dopamine D2 , Receptors, Dopamine , Receptors, Serotonin, 5-HT2 , Risperidone , Sensory Receptor Cells , SerotoninABSTRACT
By designing the circuit structure of preamplifier and selecting new elements such as ultra low noise operational amplifier and linear opto-coupler,some difficulties in EEG acquisition is overcome and the Common Mode Rejection Ratio(CMRR) of preamplifier is highly increased.So EEG can be amplified and detected well.